17. Using domain\s_sp_sql
as the account here. [I wanted to have separate account for PowerPivot services]
Click Next. Use the same account for one more installation of Analysis server
on the same farm.

18. Add the s_sp_setup
by clicking Add Current User. Click Next. Both s_sp_sql and s_sp_setup has
same level of permissions. But s_sp_sql will
run the SSAS service.

19. Click Next.

20. Click Next

21. Click Install.

Progress is shown below

22. Click OK

23. Click Close.

24. Go to services.msc.
You will see SQL Server Analysis Services
(POWERPIVOT) running under SQL Account [domain\s_sp_sql]. Restart the machine.